WASHINGTON (AP) _ Severe food shortages are forcing some North Koreans to forage for wild grasses and herbs and causing alarming malnutrition among children, U.S.-based aid groups who recently visited the reclusive country reported Wednesday.

Heavy rains and flooding in summer reduced vegetable crops by more than 50 percent in some areas, and a bitter winter has frozen up to 50 percent of wheat and barley due to be harvested in spring, the groups said in a joint statement. North Korean authorities estimate that food stocks will be exhausted by mid-June, they said.

Seven experts from five nongovernment agencies _ Christian Friends of Korea, Global Resource Services, Mercy Corps, Samaritan's Purse and World Vision _ conducted a food needs assessment between Feb. 8-15 at North Korea's request. They were granted ``extraordinary access'' to the provinces of North Pyongan, South Pyongan and Chagang, visiting 45 sites including hospitals, orphanages, homes, cooperative farms and warehouses.

``The team observed children suffering from acute malnutrition, as well as evidence of stunting, wasting, and hunger-induced listlessness,'' the statement said. 

The agencies recommended emergency food assistance targeting children, the elderly, the chronically ill, and pregnant and nursing mothers.

North Korea has reportedly asked the United States and other nations to consider resuming food aid. North Korea has faced chronic food shortages due to economic mismanagement and natural disasters for the past two decades, and suffered a famine in the early and mid 1990s.

The U.N. is also currently conducting a food needs assessment there.

International donors will be cautious in resuming food aid to North Korea without strong safeguards on monitoring its distribution, amid concerns that it could be diverted to feed the military. The U.S. government suspended food handouts in 2009, conducted with the help of the five nongovernment agencies, after monitors were expelled.

International donors would also be leery of aiding a government accused of two deadly, unprovoked military attacks on U.S. ally South Korea in the past year. The North also recently revealed it had developed a new means of generating fissile material that might be used for a nuclear bomb, and talks on it disarming its nuclear programs have stalled for nearly two years.

Rising concern over the humanitarian situation could force the issue.

   The five U.S. aid groups said that North Korea's total agricultural production was reported at 5.12 million metric tons in 2010, below the national food need of 7.93 million metric tons for a population of 24 million people. Rising global food prices has also prompted North Korea to scale back its planned purchases from abroad to just metric 200,000 tons, they said.

Among those worst hit by the shortages are families dependent on the communist state's public distribution system, with rations already cut to meager levels, the statement said.    

It said the team had found evidence of ``alarming'' malnutrition, and that local hospitals reported an increase in low birth-weight babies, reduced ability of mothers to breast feed, and increased recovery time from illness.

The groups recommended that food aid be shipped between May and June before the fall harvest.